flutter: FormatException: Unterminated string while decoding long stream response - json

Question

I was working on a flutter package that I made https://github.com/pratikbaid3/flutter_client_sse. This is used to consume server-sent events. This works fine when the response returned is comparatively small. But as soon as the response grows large, I start getting this error flutter: FormatException: Unterminated string
This is the code snippet used to get the sse
while (true) {
try {
_client = http.Client();
var request = new http.Request("GET", Uri.parse(url));
request.headers["Cache-Control"] = "no-cache";
request.headers["Accept"] = "text/event-stream";
request.headers["Cookie"] = token;
Future<http.StreamedResponse> response = _client.send(request);
await for (final data in response.asStream()) {
await for (final d in data.stream) {
final rawData = utf8.decode(d);
final event = rawData.split("\n")[1];
if (event != null && event != '') {
yield SSEModel.fromData(rawData);
}
}
}
} catch (e) {
print('---ERROR---');
print(e);
yield SSEModel(data: '', id: '', event: '');
}
await Future.delayed(Duration(seconds: 1), () {});
}
My guess is that a part of the response is lost due to the large size.

Answer 1

So after hours of debugging, I found that in my current approach when the response is very large, part of it is truncated (Not sure why). I changed the code to read one line at a time and got it to work.
data.stream
..transform(Utf8Decoder())
.transform(LineSplitter())
.listen((dataLine) {
//Do what you want with the data here
}
This seemed to solve the issue.
The complete code can be found at https://github.com/pratikbaid3/flutter_client_sse